Salmonella spp. and Campylobacter spp. are the leading causes of foodborne bacterial gastroenteritis diseases in many countries, with poultry and poultry products representing major sources for foodborne Salmonella and Campylobacter. The estimated annual costs of medical care and lost productivity due to foodborne Salmonella infections is about $2.3 billion in the United States. USDA data showed that in the United States the average prevalence of Salmonella on broilers in 1998-2002 was 10.9%; the average prevalence of Salmonella in ground chickens in 1998-2002 was 19.8%. The two figures for 2002 were 11.5 and 29.1%, respectively.
The estimated annual cost of foodborne Campylobacter infections in the United States ranges from 0.8 to $5.7 billion. Commercial broiler chickens frequently carry C. jejuni in their intestines at levels of 104-108 colony forming units (cfu) per gram of cecal matter before slaughter. Before and during slaughter and carcass processing, fecal matter can contaminate meat. Studies have revealed as many as 45 to 85% of retail poultry products are contaminated by C. jejuni with levels up to 106 cfu per fresh chicken carcass (Doyle, 1984; Genigeorgis et al., 1986; Skirrow and Blaser, 1991; Jones et al., 1991; Stem et al., 1995).
Currently, no commercial chickens are resistant to Campylobacter spp. or Salmonella spp. colonization. Preventing contamination of poultry products with foodborne pathogens, such as Salmonella and Campylobacter, remains a major challenge for poultry producers and processors. Salmonella and Campylobacter colonization of chickens can arise by vertical transmission from infected breeder birds via the hatchery, use of contaminated feed, or exposure to Salmonella or Campylobacter from a variety of environmental sources, including wild birds, rodents, insects and fomites. Farm personnel also may introduce pathogens into chicken houses, when adequate precautions are not taken.
Considering the widespread presence of Campylobacter spp. and Salmonella spp. in the environment, it is unlikely that poultry can be completely protected from Campylobacter spp. and Salmonella spp. exposure. Therefore, researchers have continued to investigate means of increasing resistance to colonization in poultry exposed to Campylobacter spp. and Salmonella spp. One such method involves the use of competitive exclusion bacterial strains.
Competitive exclusion (CE) is the treatment of newly hatched chicks with a source of natural bacterial populations, including for example, the administration of suspensions of cecal or fecal contents obtained from healthy adult birds, to prevent colonization by enteropathogens. For example, indigenous intestinal flora from healthy adults has been reported to provide a protective effect against Salmonella colonization in young chicks (see Snoeyenbos et al., Avian Dis. 23:904-913 (1979), Schneitz et al., Acta Pathol. Microbiol. Scand. Sect. B., 89:109-116, (1981), and Stavric et al., J. Food Prot., 48:778-782, (1985)).
CE cultures of unknown bacterial composition are called undefined CE cultures; and CE cultures of a known bacterial composition are called defined CE cultures. To date, only cultures of normal microflora that contain an undefined mixed population of several hundred different micro-organisms have proven to effectively inhibit Salmonella growth. The sale and use of undefined CE culture is acceptable in some countries. However, in the United States, undefined CE cultures are prohibited for use in poultry production by government regulations out of concerns that the undefined product may contain pathogens for human. Furthermore, because of the undefined number and types of micro-organisms present in mixed cultures, the undefined compositions cannot be standardized, and thus the product cannot be stored or produced on a large scale without changes in composition and effectiveness.
One aspect of the present invention is directed to a novel composition comprising a defined competitive exclusion (CE) culture that will prevent or substantially reduce/eliminate Salmonella and other enteropathogen colonization in commercial poultry, including broiler chickens and turkeys. The CE culture may include a single bacterium or may include a mixture of several bacterial isolates.